Electrically variable vehicle transmissions (EVTs), such as those described in U.S. Pat. No. 5,931,757, employ two electric motor/generators. The electric motor/generators are coaxially oriented with an input shaft connectable to an engine, an output shaft, and a plurality of planetary gearsets each having respective first, second, and third members. Each motor/generator is operatively connected to a respective member of one of the planetary gearsets to provide a range or mode of transmission operation characterized by a continuously variable speed ratio between the input shaft and the output shaft. The continuously variable speed ratio is proportional to the speed of one of the motor/generators.
In light vehicles using gasoline or hydrogen engines, electrical friction losses in EVT motor windings, iron, and controllers may become more significant than in heavy-duty vehicles. These engines may not be as sensitive to speed for emissions, so some of the advantages of an electrically variable transmission may not be as significant in very light vehicles compared to heavy-duty vehicles.